This invention relates to a method of making color filter arrays for a device such as an image sensor. The color filter has at least two systems of different colored filter elements each passing different colors of light. These filter elements are formed by coloring with dyes.
An example of a color imaging device which uses color filter arrays is shown in U.S. Pat. No. 4,081,277 and is used for recording video images. In this patent, the imaging device is a semiconductor layer which as a system of photosensitive elements. The color filter is provided directly on the system of photosensitive elements. The color filter is a single layer having systems of filter elements passing light of various colors, for example, red, green and blue. The filter elements are generally less than 50.mu.m and are usually squares or stripes and are placed in registration with the photosensitive elements of the semiconductor layer.
The application of color filters as currently practiced is based upon sequentially coating, exposing, developing and dyeing a light-sensitive mordant or a mixture of a light-sensitive photoresist and mordant. In this way, three separate dyed regions, each containing subtractive dyes (i.e., cyan, magenta and yellow) are produced in registration with each other so that the red, green and blue filter elements are formed. This process requires three crucial aligning steps during exposure and appropriate process control so that voids between the filters which would result in white spots are avoided.
Unfortunately, the manufacture of color filters in the above-described manner may give rise to color defects and error in the registration of the filter elements with respect to the photosensitive elements. Moreover, there is a problem of dye diffusion in that the dye can easily travel outside the region to be colored.